1. Field of the Invention
The present invention relates to an electrode for measuring an electrocardiogram and an electrocardiogram device including the electrode, and more particularly, to an electrode for measuring an electrocardiogram, which is robust against motion artifacts, and an electrocardiogram measuring device including the electrode.
2. Description of the Related Art
An electrocardiogram is a recording of an action current produced by contraction and expansion of cardiac muscles, which is measured by attaching an electrode to the surface of the body. The active potentials generated during systole and diastole cause electrical currents to propagate from the heart to the rest of the body, the electrical currents generate a potential difference between different parts of the body, and the potential difference is measured and recorded through a surface electrode attached to the skin of the body. The electrocardiogram is used to detect whether there is a problem in the heart, and is importantly used for diagnosis of heart disease, such as angina pectoris, myocardial infraction, and arrhythmia, as a basic diagnostic element.
In general, a device for measuring the electrocardiogram includes an electrode that contacts the skin and measures the active potential, a power supply, and a controller that interprets and processes the measured active potential signal.
The device for measuring the electrocardiogram may be a wireless or wired device. A wired device for measuring an electrocardiogram, which is generally used in a hospital, has an electrode that contacts the skin and is connected to the power supply and the controller. The wireless device for measuring the electrocardiogram includes an electrode that contacts the skin, a power supply, a controller, and a transceiver that transmits and receives a signal.
The electrode is classified as a wet-type electrode or a dry-type electrode according to whether the electrode includes an electrolyte. The dry-type electrode is placed on a region of the chest using an elastic band. However, there is chest pressure when the dry-type electrode is placed on the thorax, and therefore a device including the dry-type electrode is not desirable to be used for a long period of time. Further, if the electrode is initially loosely attached to a user or the humidity of the electrode is lowered by long-term use of the electrode, the quality of a signal may be deteriorated.
Meanwhile, the wet type electrode does not require an additional band, but uses adhesive materials. FIG. 1(a) is a bottom view of the conventional wet type electrode, and FIG. 1(b) is a top view of the conventional wet type electrode. The bottom view represents a skin contact surface, and the top view represents a controller contact surface. Referring to FIG. 1A, the skin contact surface of the conventional wet type electrode is formed by a signal detector 102 and a skin contact portion 104. The signal detector 102 is covered with an electrolytic gel, and the skin contact portion 104 is covered with an adhesive material. Referring to FIG. 1B, the controller contact surface is formed by a controller connector 106 and the skin contact portion 104.
The conventional wet type electrode uses the adhesive material, which induces pain and loss of hair from the skin when the electrode is detached from the skin. Moreover, since the adhesion of the electrode is lowered as time passes, the electrode is detached from the skin and easily exposed to the outside, and consequently the quality of the signal is deteriorated by drying of the electrolyte or breaking of the conductivity between the electrode and the skin. Therefore, the wet type electrode is not suitable to be used for a long period of time. Further, since the skin contact portion is enlarged to improve the adhesion between the electrode and the skin and the signal detector is relatively small in the total area of the electrode, the device including the wet type electrode cannot robustly deal with motion artifacts due to the movements of the body.
There are several conventional inventions related to the electrocardiogram measurement device. For example, Japanese Patent Laid-open Gazette No. 2001-269322 discloses a signal measurement device which includes a base sheet having a circuit unit that acquires an electrocardiogram and transmits and receives an electrocardiogram signal measured by an electrode is placed on the thorax of the body. Additionally, U.S. Pat. No. 5,862,803 discloses a device for diagnosis and monitoring, which includes a semiconductor chip having an electrode that includes a transceiver and a battery and is integrated on the semiconductor chip and is attached to the skin of a patient. However, the conventional inventions use the conventional wet type or dry type electrodes, and thus cannot solve the above problems.